I am not an expert on Patek Philippe; sure I know something here and there and esp in the niches, but there are for sure others with more expertise -- especially when it comes to the full variety of historical references.

I need to know: was the Patek Ellipse ref3738 or the Patek Nautilus ref3700 their first use of a monocoque-case? These would both date to 1977 / 1978 but the question is, whether there were earlier references using the case without a openable caseback; so something before 1977?

If you know of any Patek-ref before that time that used a monocoque please let me know -- send a message to info@plus-ultra.ch: thank you a lot in advance!

* UPDATE 2026-02-22:* After consulting some of the capacities in vintage Patek it seems like the 3700 or 3738 in 1977 or 1978 is indeed their first monocoque. And that could shed some light on Pateks flagship ref3738 from a very surprising direction... for now, lets keep in mind that the diameter of an Ellipse ref3738 as an round Calatrava would be 34mm and that the development cycles for new watches at Patek Philippe is something between 3 and 6 years. Is it possible we can find Pateks technical inspiration for the Jumbo ref3738 five years earlier (1973) somewhere we would never expect it? I am not speaking about the characteristic design or the iconic dial color but the so far overlooked special monocoque-case -- a technically superior solution.

However, if you know any earlier Patek-monocoque I am looking forward to hear about it.